AT LEAST 18 people were injured in a series of Israeli air strikes on Gaza City.

It was reported that there were up to nine explosions in the city and in the north and south of the territory, with militant training camps operated by Hamas among the targets, the BBC News reports.

The Israeli military says its aircraft struck two militant tunnels, two weapons manufacturing and storage facilities and two other militant sites across the Gaza Strip.

Palestinian health official Adham Abu Salmia reported that 18 civilians and Hamas security forces were slightly wounded.

The military said Tuesday that the sites were targeted overnight in response to 56 mortar shells and rockets fired from Gaza into Israel over the past week.

In a statement, it vowed to “respond with determination” to any attempt to attack Israelis.

Palestinian militants fired two rockets into southern Israel on Sunday and Israeli troops killed two Palestinians in a new outburst along the volatile border with Gaza.

The violence came a day after Palestinian militants fired more than 50 mortar shells into Israel — the heaviest Palestinian barrage since a bruising Israeli military offensive in Gaza two years ago.

The Hamas-allied Popular Resistance Committees claimed responsibility for Sunday morning’s rocket attack, which caused no injuries or damage.

Militants in Gaza fired another rocket into southern Israel in the evening, exploding near the city of Ashkelon. No one was hurt.

Gaza Health Ministry spokesman Adham Abu Salmia said rescue teams recovered the bodies of two Palestinian men who were killed overnight along the border. The Israeli military said soldiers spotted two Palestinians crawling toward the border with what appeared to be a bomb. Soldiers called on them to stop, and opened fire after they continued moving toward the border.

Israel’s UN ambassador, Meron Reuben, sent a letter of complaint to Secretary-General Ban Ki-moon and the Security Council, demanding that they condemn rocket and mortar barrages on Israel.

On Saturday, Hamas police assaulted protesters and journalists at a demonstration calling for reconciliation. New York-based Human Rights Watch criticized Hamas for Saturday’s crackdown, and a similar one at a demonstration last Tuesday.

- Additional reporting by AP